Operational Life Tests (OLTs) provide measures of the reliability of integrated circuit devices (ICs). An OLT achieves this by continually exercising a component such as an IC, or a plurality of components simultaneously. OLTs also include testing in a chamber having a controlled environment, with instrumentation controlled to simulate use by a customer.
During operational life testing a plurality of semiconductor devices are mounted on burn-in boards which are interconnected for operation in either series or parallel depending on the test to be performed. While the devices are being electrically tested, the temperature within the chamber is cycled to simulate temperature cycling experienced by the devices during normal use. It has been found that with operational life testing infant mortality rates can be determined, which aids in avoiding early failures in the field. Additionally, reliability problems can be dealt with by component "burn-in" which includes testing the devices at increased temperature to induce infant mortality failures at the factory.
The concept of burn-in is a method for screening out early failures in a group of devices prior to their introduction into general service by a customer. The burn-in process involves time as an important factor since the elements to be tested are monitored for failure either continuously or at a predefined time sequence. A goal with respect to burn-in is to provide an adequate burn-in period to detect infant mortals while testing devices no longer than necessary.
The controls of typical burn-in systems are interconnected with large cables from their power supplies. The cables are difficult to connect and contribute to large, heavy equipment. Repairing the equipment can be a complex process because of the complex designs of typical testing and burn-in equipment. Typical testing equipment requires a number of power supplies to test the large number of device under test boards loaded into the environmental chamber (oven).